JP7389766B2 - Terminal parts, secondary batteries and assembled batteries equipped with the same, and method for manufacturing terminal parts - Google Patents

Description

The present invention relates to a terminal component, a secondary battery and an assembled battery including the same, and a method for manufacturing the terminal component.

Japanese Unexamined Patent Publication No. 2016-18675 discloses joining a metal member to the external terminal by ultrasonic joining in order to improve the weldability between the external terminal and the bus bar. JP-A No. 2011-124024 discloses that after a base to which a current collector foil is connected and an external terminal are joined by ultrasonic bonding, the joint is further caulked to improve the joint strength of both parts. It is disclosed that it allows

Japanese Patent Application Publication No. 2016-18675 Japanese Patent Application Publication No. 2011-124024

When different metals are bonded to a terminal by metal bonding such as ultrasonic bonding, the bonding strength between the terminal and the metal may be insufficient. Therefore, after joining, a process such as creating a separate caulking structure between the joined parts is added to strengthen the joint strength between the metal-welded parts. In addition, when attempting to secure the necessary bonding strength only by metal bonding, it is necessary to bond a wide range of contact surfaces between parts using high energy. Such a joining method may cause roughness or deformation on the surface of the external terminal. Removing roughness and deformation on the surface of the external terminal by post-processing increases the number of steps and is not preferable from the viewpoint of productivity.
The present inventor would like to provide a terminal component for a secondary battery made of two metals that are joined with sufficient joint strength and are electrically conductive. At the same time, we would like to provide technology for manufacturing such terminal components with a reduced number of steps.

The terminal component disclosed herein includes a first metal and a second metal overlaid on the first metal. The first metal is provided with a recess that is wider inside than the opening at a portion where the second metal is overlapped. A part of the second metal has entered the recess of the first metal, and a part of the second metal has entered the part of the recess of the first metal that is wider than the opening, and a part of the second metal has entered the recess of the first metal. has a recess formed on the opposite surface. At least a portion of the second metal that has entered the recess of the first metal is metal-bonded to the inner surface of the recess of the first metal.

In such a terminal component, the second metal enters a portion of the recess of the first metal that is wider inside than the opening, thereby ensuring the bonding strength between the first metal and the second metal. Furthermore, at least a portion of the second metal that has entered the recess of the first metal is metal-bonded to the inner surface of the recess of the first metal, thereby ensuring conduction between the members.

In the terminal component disclosed herein, the first metal may be more rigid than the second metal.
The diameter D ₁ of the recess of the first metal and the diameter D ₂ of the opening may satisfy the relationship 0.4≦D ₂ /D ₁ ≦0.95. A further recess may be formed at the bottom of the recess of the first metal. The recess formed at the bottom may be provided with a portion that becomes wider in the depth direction from the opening.
In the terminal component, the first metal may be made of copper or a copper-based alloy, and the second metal may be made of aluminum or an aluminum-based alloy.

Other aspects of the technology disclosed herein include an electrode body including a positive electrode and a negative electrode, a battery case housing the electrode body therein, and a positive terminal and a negative electrode electrically connected to the positive electrode and the negative electrode in the electrode body, respectively. A secondary battery comprising a terminal is provided. At least one of the positive terminal and the negative terminal of the secondary battery includes the terminal component disclosed herein.
Another aspect of the technology disclosed herein is an assembled battery in which a plurality of unit cells are electrically connected to each other and arranged, and the plurality of unit cells include the terminal components disclosed herein. A battery pack using a secondary battery is provided. In the plurality of cells, the positive terminal of one cell and the negative terminal of the other cell are electrically connected by a bus bar. The bus bar may be made of the same metal as the second metal.

The method for manufacturing a terminal component disclosed herein includes a step of preparing a first metal having a recess whose inside is wider than an opening, a step of preparing a second metal, and a step of metal-bonding the first metal and the second metal. process. The step of metal-bonding the first metal and the second metal is to overlay the second metal on the part where the recess is formed in the first metal, and partially attach the second metal to the position corresponding to the recess of the first metal. Pressure is applied to form a recess in the second metal, and a part of the second metal is inserted into a part that is wider inside than the opening of the recess in the first metal, and the part of the second metal that has entered the recess in the first metal is and the first metal.

In such a manufacturing method, in the step of metal-bonding the first metal and the second metal, the second metal is partially pressurized, and a part of the second metal is applied to a portion whose inside is wider than the opening of the recess of the first metal. I'm letting them in. Thereby, there is no need to provide a separate step of mechanically joining the first metal and the second metal by a method such as caulking, and the above-mentioned terminal component can be manufactured with a reduced number of steps.
Further, by performing the metal bonding between the first metal and the second metal inside the recess of the first metal, it is possible to suppress roughness and deformation that may occur on the surface connected to the bus bar. As a result, the number of processing steps for dealing with roughness and deformation of the surface to which metal bonding is performed can be reduced.

In the method for manufacturing a terminal component disclosed herein, in the step of preparing the second metal, a second metal having lower rigidity than the first metal may be prepared.
In the step of preparing the first metal, a first metal is prepared in which the diameter D ₁ of the recess and the diameter D ₂ of the opening satisfy the relationship 0.4≦D ₂ /D ₁ ≦0.95. You can. Further, in the step of preparing the first metal, the first metal may be further formed with a recess at the bottom of the recess. The recess formed at the bottom may be provided with a portion that becomes wider in the depth direction from the opening.
In the step of preparing a first metal, a first metal made of copper or an alloy mainly composed of copper is prepared, and in the step of preparing a second metal, a first metal made of aluminum or an alloy mainly composed of aluminum is prepared. Two metals may be prepared.
In the step of metal joining the first metal and the second metal, the metal joining may be performed by ultrasonic pressure welding, friction welding, or resistance pressure welding.

1 is a perspective view schematically showing the outer shape of a secondary battery 12. FIG. 1 is a perspective view schematically showing an assembled battery 10 made up of single cells 12. FIG. 2 is a wide cross-sectional view schematically showing the internal structure of a secondary battery 12. FIG. 2 is a narrow cross-sectional view schematically showing the internal structure of a secondary battery 12. FIG. FIG. 3 is a cross-sectional view schematically showing the structure of the lid body 34 to which the terminal component 54 is attached. 5 is a cross-sectional view schematically showing a terminal component 54. FIG. FIG. 7 is a cross-sectional view schematically showing a terminal component 54 according to another embodiment. FIG. 5 is a cross-sectional view illustrating a method of manufacturing a terminal component 54. FIG. FIG. 5 is a cross-sectional view illustrating a method of manufacturing a terminal component 54. FIG.

Hereinafter, embodiments of a terminal component proposed here, a secondary battery equipped with the terminal component, an assembled battery having a unit cell equipped with the terminal component as a component, and a method for manufacturing the terminal component will be described. A prismatic lithium ion secondary battery with a body will be described in detail as an example.

In this specification, "secondary battery" is not limited to the lithium ion secondary battery described below, but includes, for example, a sodium ion secondary battery, a magnesium ion secondary battery, or a so-called physical battery. This concept includes lithium ion capacitors and the like. In addition, although a lithium ion secondary battery equipped with a wound electrode body having a structure in which a plurality of positive electrode and negative electrode bodies are wound with separators in between is explained here, the electrode body is limited to such a structure. Alternatively, a plurality of positive electrode and negative electrode bodies may be stacked with a separator in between.

In the following drawings, the same reference numerals are given to members and parts that have the same function, and overlapping explanations may be omitted or simplified. Dimensional relationships such as length and width in the drawings below do not necessarily reflect actual dimensional relationships.
In this specification, when a numerical range is described as A to B (where A and B are arbitrary numerical values), it means a range of A to B. In addition, in this specification, the term "main body" refers to a component that occupies the maximum weight among arbitrary constituent components; for example, when the total weight of the constituent components is 100 parts, the term "main body" refers to a component that occupies 50 parts by mass or more of the constituent components. Refers to ingredients.
In this specification, metal bonding refers to a bonded state in which metals are directly bonded to each other at a bonding interface without using an adhesive or the like. Metallic bonding is realized, for example, by ultrasonic bonding, friction welding, diffusion bonding, resistance welding, etc., and mechanical bonding conditions such as caulking are excluded.

FIG. 1 is a perspective view schematically showing the outer shape of the secondary battery 12. As shown in FIG.
The secondary battery 12 is a secondary battery that can be repeatedly charged and discharged, and is, for example, a lithium ion secondary battery. Although a detailed description of the structure will be omitted, the secondary battery 12 disclosed herein includes an electrode body 20 inside a battery case 30, which has a structure in which a positive electrode and a negative electrode are stacked with a separator in between. The electrode body is housed in the battery case body 32 together with a non-aqueous electrolyte (not shown), and the edge of the lid body 34 is sealed by welding or the like while the inside is depressurized. The battery case 30 is made of a metal material that is lightweight and has good thermal conductivity, such as aluminum, for example. The shape of the battery case 30 is not limited to the rectangular shape shown in FIG. 1, and may be, for example, cylindrical.

The secondary battery 12 includes a positive terminal 40 and a negative terminal 50 at the top of the battery case 30. The positive electrode terminal 40 and the negative electrode terminal 50 are electrically connected to an electrode body inside the battery case, and are connected to the outside via a bus bar. The shapes of the positive electrode terminal 40 and the negative electrode terminal 50 are not particularly limited, and may be rectangular as shown in the figure, or may be circular, including an elliptical shape, for example.

FIG. 2 is a perspective view schematically showing an assembled battery 10 made up of single cells 12. As shown in FIG.
In an assembled battery 10 in which a plurality of secondary batteries 12 shown in FIG. 1 are arranged as unit cells 12, the unit cells 12 are arranged with spacers 11 in between. A pair of end plates 17 are arranged further outside of the outermost spacer 11. These are restrained by a tightening beam member 18 attached to bridge the end plate 17, and the ends of the tightening beam member 18 are tightened and fixed with screws 19.

In the assembled battery 10 , the positive terminal 40 of the unit cell 12 is electrically connected to the negative terminal 50 of another adjacent unit cell 12 via the bus bar 14 . As the bus bar 14, aluminum, copper, or the like is used, for example.

FIG. 3 is a wide sectional view schematically showing the internal structure of the secondary battery 12. As shown in FIG.
The electrode body 20 is a power generation element housed inside the battery case 30 while being covered with an insulating film or the like (not shown). The electrode body 20 includes a positive electrode sheet 21 as a positive electrode element, a negative electrode sheet 22 as a negative electrode element, and separator sheets 23 and 24 as separators. The positive electrode sheet 21, the negative electrode sheet 22, and the separator sheets 23 and 24 are each long strip-shaped members. In this embodiment, the electrode body 20 is a wound electrode body in which a positive electrode sheet 21, a negative electrode sheet 22, and separator sheets 23 and 24 are wound together.

The positive electrode sheet 21 includes a foil-shaped positive electrode current collector 21A, and a positive electrode active material layer 21B formed along the longitudinal direction on one or both surfaces of the positive electrode current collector 21A. Further, the positive electrode active material layer 21B is not formed on one side edge of the electrode body 20 in the width direction of the secondary battery 12, and the positive electrode current collector exposed portion 21C where the positive electrode current collector 21A is exposed is It is provided. As the positive electrode current collector 21A, aluminum foil or the like is used. The positive electrode active material layer 21B includes various materials such as a positive electrode active material, a binder, and a conductive material.
A positive electrode current collector terminal 42 is connected to the positive electrode current collector exposed portion 21C. As the positive electrode current collector terminal 42, for example, aluminum foil or the like is used. Regarding the materials contained in the positive electrode active material layer 21B, materials that can be used in conventional general lithium ion secondary batteries can be used without particular restriction, and detailed explanations are omitted because they do not characterize the present invention. do.

The negative electrode sheet 22 includes a foil-shaped negative electrode current collector 22A and a negative electrode active material layer 22B formed along the longitudinal direction on one or both surfaces of the negative electrode current collector 22A. Moreover, the negative electrode active material layer 22B is not formed on the other side edge of the electrode body 20 in the width direction, and a negative electrode current collector exposed portion 22C in which the negative electrode current collector 22A is exposed is provided. Copper foil or the like is used as the negative electrode current collector 22A. Similar to the positive electrode active material layer 21B, the negative electrode active material layer 22B includes various materials such as a negative electrode active material and a binder.
A negative electrode current collector terminal 52 is connected to the negative electrode current collector exposed portion 22C. As the negative electrode current collector terminal 52, for example, copper foil or the like is used. Regarding the material contained in the negative electrode active material layer 22B, materials that can be used in conventional general lithium ion secondary batteries can be used without particular restriction, and detailed description is omitted because it does not characterize the present invention. do.

Separator sheets 23 and 24 are interposed between positive electrode sheet 21 and negative electrode sheet 22 to prevent these electrodes from coming into direct contact. Although not shown, a plurality of fine holes are formed in the separator sheets 23 and 24. The fine holes are configured so that charge carriers (lithium ions in the case of a lithium ion secondary battery) move between the positive electrode sheet 21 and the negative electrode sheet 22.
For the separator sheets 23 and 24, a resin sheet or the like having the required heat resistance is used. As the separator sheets 23 and 24, those that can be used in conventional general lithium ion secondary batteries can be used without particular limitation. Since the separator sheets 23 and 24 do not characterize the present invention, a detailed description of the separator sheets 23 and 24 will be omitted.

As the non-aqueous electrolyte contained in the battery case 30, any one that typically contains a non-aqueous solvent and a supporting salt and that can be used in conventional general lithium ion secondary batteries can be used without particular limitation. be able to. Since the non-aqueous electrolyte does not characterize the present invention, a detailed explanation of the non-aqueous electrolyte will be omitted.

FIG. 4 is a narrow cross-sectional view schematically showing the internal structure of the secondary battery 12. As shown in FIG. The negative terminal 50 (see FIG. 1) is composed of a negative current collector terminal 52 and a negative external terminal 54. In this embodiment, the negative electrode current collector terminal 52 is made of a single plate-shaped member made of copper. As shown in FIG. 4, the negative current collector terminal 52 is bent inside the battery case 30 and connected to the negative external terminal 54 and the electrode body 20. The negative external terminal 54 is connected to the negative current collector terminal 52, and a portion thereof is exposed on the outer surface of the lid 34.

Similarly, the positive terminal 40 includes a positive current collector terminal 42 and a positive external terminal 44. In this embodiment, the positive current collector terminal 42 is made of a single plate-shaped member made of aluminum. The positive current collector terminal 42 is bent inside the battery case 30 and connected to the positive external terminal 44 and the electrode body 20 . The positive external terminal 44 is connected to the positive current collector terminal 42 and is partially exposed on the outer surface of the lid 34 .

By the way, aluminum is suitably used for the positive electrode current collector 21A of the electrode body 20. Copper foil is suitably used for the negative electrode current collector 22A of the electrode body 20. It is preferable that the same type of metal as the current collectors to be connected is used for the positive electrode current collector terminal 42 and the negative electrode current collector terminal 52, respectively. Therefore, it is preferable that aluminum be used for the positive electrode current collector terminal 42. It is preferable that copper is used for the negative electrode current collector terminal 52. Further, aluminum is preferably used for the bus bar 14 from the viewpoint of conductivity and lightness. Therefore, when copper is used for the negative electrode current collector terminal 52 and the negative electrode external terminal 54 and aluminum is used for the bus bar 14, the negative electrode current collector terminal 52 and the negative electrode external terminal 54 and the bus bar 14 are made of metal. The species will be different. In response to this, the present inventor is considering adopting a terminal component in which aluminum and copper are bonded to each other as the negative external terminal 54.

Below, the terminal component disclosed herein will be explained based on a configuration in which the terminal component is used as the negative external terminal 54. Note that in the case where the positive electrode terminal 40 side has the terminal components disclosed herein, the configuration is the same as that of the negative electrode terminal 50 side, so the explanation will be omitted.

FIG. 5 is a cross-sectional view schematically showing the structure of the lid body 34 to which the terminal component 54 is attached. FIG. 6 is a cross-sectional view schematically showing the terminal component 54. As shown in FIG. The terminal component 54 is attached to the lid body 34 via the gasket 36. The negative current collector terminal 52 is attached to the lid 34 via the insulator 38.

As shown in FIG. 5, the lid body 34 has a mounting hole 34A for mounting the terminal component 54 at a predetermined position. A negative electrode current collector terminal 52 and a terminal component 54 are attached to the attachment hole 34A of the lid body 34 with a gasket 36 and an insulator 38 interposed therebetween.

The terminal component 54 includes a first metal 60 and a second metal 64. As shown in FIGS. 5 and 6, the first metal 60 constituting the terminal component 54 includes a shaft portion 60A, an upper end portion 60B, and a caulking portion 60C. The shaft portion 60A is a portion that is attached to the attachment hole 34A via the gasket 36. The shaft portion 60A has a cylindrical shape. The upper end portion 60B is a portion disposed on the outside of the lid body 34. The upper end portion 60B is a substantially flat portion larger than the attachment hole 34A. The caulking portion 60C is a portion that is caulked to the negative electrode current collector terminal 52 inside the lid body 34, as shown in FIG. The second metal 64 is stacked on the upper end 60B of the first metal 60. On the surface where the second metal 64 overlaps the upper end portion 60B, the surfaces of the second metal 64 and the upper end portion 60B have the same shape. The detailed structure of the terminal component 54 will be described later.

The gasket 36 is a member that is attached to the attachment hole 34A of the lid 34, as shown in FIG. The gasket 36 includes a flat plate portion 36A, a side wall portion 36B, and a cylindrical portion 36C. The flat plate portion 36A has a shape that matches the surface of the terminal component 54 facing the lid 34. The side wall portion 36B extends perpendicularly from the peripheral edge of the flat plate portion 36A. The cylindrical portion 36C protrudes from the bottom of the flat plate portion 36A. The cylindrical portion 36C has an outer shape that follows the inner surface of the attachment hole 34A. The cylindrical portion 36C serves as a mounting hole into which the shaft portion 60A of the first metal 60 constituting the terminal component 54 is mounted.
The gasket 36 is an insulating resin member, and insulates the terminal component 54 and the lid 34. The gasket 36 ensures airtightness of the mounting hole 34A of the lid 34. From this point of view, it is preferable to use a material with excellent chemical resistance and weather resistance as the gasket 36. As the gasket 36, for example, a fluororesin such as perfluoroalkoxy alkane (PFA) is used.

The insulator 38 is a member that is attached to the inside of the lid 34 around the attachment hole 34A of the lid 34. The insulator 38 is a substantially flat member. The insulator 38 includes a through hole 38A. A shaft portion 60A of the first metal 60 that constitutes the terminal component 54 is inserted into the through hole 38A. The through hole 38A has a shape that corresponds to the outer shape of the shaft portion 60A of the first metal 60 that constitutes the terminal component 54.
The insulator 38 is a resin member having insulation properties. The insulator 38 insulates the lid body 34, the negative electrode current collector terminal 52, and the terminal component 54. Since the insulator 38 is disposed inside the battery case 30, it is preferable that the insulator 38 has the required chemical resistance. As the insulator 38, polyphenylene sulfide (PPS) or the like is used, for example.

The negative electrode current collector terminal 52 is made of a single plate-shaped member as described above. The negative electrode current collector terminal 52 is arranged inside the insulator 38. The negative electrode current collector terminal 52 includes a through hole 52A. A shaft portion 60A of the first metal 60 that constitutes the terminal component 54 is inserted into the through hole 52A. The through hole 52A has a shape that corresponds to the outer shape of the shaft portion 60A of the first metal 60 that constitutes the terminal component 54. The negative electrode current collector terminal 52 is provided with a step 52B around the through hole 52A. The tip of the caulked portion 60C of the first metal 60 is hooked and fixed to the step 52B.

In this embodiment, the gasket 36 is attached to the outside of the lid 34 while the cylindrical portion 36C of the gasket 36 is attached to the attachment hole 34A of the lid 34. Further, the terminal component 54 is attached to the gasket 36. At this time, the shaft portion 60A of the first metal 60 is inserted into the cylindrical portion 36C of the gasket 36, and the upper end portion 60B of the first metal 60 is placed on the flat plate portion 36A of the gasket 36. An insulator 38 and a negative current collector terminal 52 are attached to the inside of the lid 34. Then, as shown in FIG. 5, the caulking portion 60C of the first metal 60 is bent and caulked to the negative electrode current collector terminal 52. The caulked portion 60C of the first metal 60 and the negative electrode current collector terminal 52 may be partially metal-bonded to improve conduction.

The terminal component 54 includes a first metal 60 and a second metal 64. As the first metal 60, a metal having higher rigidity than the second metal 64 may be used. Here, the rigidity of the first metal 60 is such that when the second metal 64 is strongly pressed against the first metal 60, the first metal 60 does not deform but the second metal 64 deforms. It is better if it is higher than metal 64. In this embodiment, first metal 60 is comprised of copper. The second metal 64 is made of aluminum. Note that the rigidity of the first metal 60 and the second metal 64 can be evaluated by, for example, a Vickers hardness test or a tensile test.

The first metal 60 is provided with a recess 62 at a portion where the second metal 64 is overlapped. The recess 62 has a portion 62B that is wider inside than the opening 62A. In this specification, the interior-widened portion 62B means that when the opening 62A of the recess 62 of the first metal 60 is projected perpendicularly from the opening in the depth direction, the projection plane of the opening and the first It refers to the space between the metal recess.

In the present embodiment, the recess 62 of the first metal 60 has a substantially circular cross section along a cross section that traverses the same depth from the opening 62A. The area of the recess 62 of the first metal 60 gradually increases as it becomes deeper from the opening 62A. The recess 62 has a substantially truncated conical space. The area of the bottom 62C1 of the recess 62 is wider than the area of the opening 62A. The recess 62 has a cross-sectional area that becomes narrower from the bottom 62C1 toward the opening 62A, along a cross section that traverses the same depth from the opening 62A. In other words, the recess 62 has a shape in which the side circumferential surface 62C2 protrudes toward the inner diameter side with respect to the bottom portion 62C1. The recess 62 of the first metal 60 having such a shape may be formed by forging or cutting, for example.

In the embodiment described above, the recess 62 of the first metal 60 is a substantially truncated conical space whose interior is wider than the opening 62A. It is sufficient that the recess 62 has a portion that is wider inside than the opening 62A. The shape of the recess 62 is not limited to this shape. For example, in a cross section taken along the same depth from the opening 62A, the recess 62 is not limited to a circular shape, but may have a polygonal shape such as a triangular, quadrangular, pentagonal, or hexagonal shape. In this embodiment, the recess 62 of the first metal 60 is a substantially truncated conical space. The recess 62 has a portion 62B that is continuous in the circumferential direction and is wider inside than the opening.

Note that the recess 62 is not limited to this form. The recess 62 may include a portion 62B that is partially wider inside than the opening in the circumferential direction. Further, in this embodiment, the opening 62A of the recess 62 of the first metal 60 is circular, but it does not necessarily have to be circular. The opening 62A of the recess 62 only needs to be narrower than the inside of the recess 62, which has become wider. The opening 62A of the recess 62 may have, for example, a part in the circumferential direction that protrudes radially inward from the inside of the recess 62, which has become wider. In this case, it is preferable that a plurality of portions, for example, two to four portions, projecting toward the inner diameter side are provided in the circumferential direction of the recess 62.

The second metal 64 is superimposed on the first metal 60 at a portion provided with the recess 62 . In this embodiment, the peripheral edge of the second metal 64 overlaps the peripheral edge of the upper end 60B of the first metal 60. The surface of the second metal 64 opposite to the surface overlaid on the upper end 60B of the first metal 60 is exposed to the outside of the battery case 30. The exposed surface 54A is connected to a bus bar or the like.

A portion of the second metal 64 has entered the recess 62 of the first metal 60. The second metal 64 has a region 64A that enters into the recess 62 of the first metal 60, and a recess 64C formed on the opposite side of the region 64A that enters the recess 62 of the first metal 60. . Hereinafter, the portion 64A of the first metal 60 that has entered the recess 62 will be referred to as a fitting portion 64A. Further, of the fitting portion 64A, a portion 64B that enters into a portion 62B that is wider than the opening 62A in the depth direction of the recess 62 of the first metal 60 is particularly referred to as a fitting portion 64B.

As shown in FIG. 5, the second metal 64 is in contact with the bottom 62C1 of the recess 62 of the first metal 60. Further, the fitting portion 64B is inserted sufficiently deeply into a portion 62B of the recess 62 of the first metal 60, which is wider inside than the opening 62A. That is, the fitting portion 64B engages with the side circumferential surface 62C2 of the recess 62. This configuration ensures sufficient mechanical fastening strength between the first metal 60 and the second metal 64. Note that it is permissible for a gap to exist between the recess 62 of the first metal 60 and the second metal 64.

In this embodiment, the cross section of the recess 64C of the second metal 64, taken along the cross section from the opening 62A to the same depth, is approximately circular. The recess 64C of the second metal 64 is formed at a position corresponding to the recess 62 of the first metal 60. As shown in FIG. 5, in this embodiment, the recess 64C of the second metal 64 reaches a deeper position than the opening 62A of the recess 62 of the first metal 60.

The shape of the recess 64C and the shape of the bottom 64D of the second metal 64 are not limited to these embodiments. The recess 64C of the second metal 64 may have, for example, a substantially prismatic shape with a polygonal cross section such as a quadrangle. Furthermore, the bottom portion 64D does not necessarily need to be flat. For example, the bottom portion 64D may have a shape that becomes deeper from the periphery toward the center. Conversely, the bottom portion 64D may have a shape in which the periphery is deeper than the center. The depth of the recess 64C of the second metal 64 is not particularly limited. In order to bond the first metal 60 and the second metal 64 with sufficient bonding strength, the depth of the recess 64C of the second metal 64 is, for example, greater than or equal to the depth of the recess 62 of the first metal 60. Good too.

At least a portion of the portion 64A of the second metal 64 that has entered the recess 62 of the first metal 60 is metal-bonded to the inner surface of the recess 62 of the first metal 60. As described above, the fitting portion 64A of the second metal 64 is in contact with the bottom portion 62C1 of the recess 62 of the first metal 60. The fitting portion 64A is metallized to at least a portion of the inner surface of the recess 62 of the first metal 60, that is, the surface consisting of the bottom portion 62C1 and the side peripheral surface 62C2. In this embodiment, the metal bond is formed inside the plane in which the bottom 64D of the recess 64C of the second metal 64 is projected onto the bottom 62C1 of the recess 62 of the first metal 60. Here, the portion where the first metal 60 and the second metal 64 are metal-bonded is appropriately referred to as a joint portion 66. The position where the first metal 60 and the second metal 64 are metal-bonded is not limited to this. The metal bond between the first metal 60 and the second metal 64 may be formed, for example, on the side peripheral surface 62C2 of the recess 62. The joint portion 66 is joined without using an adhesive layer such as adhesive or solder. In the joint portion 66, surfaces where the first metal 60 and the second metal 64 are joined may be joined by so-called solid phase joining. At the joint portion 66 , a metal bond may occur between at least a portion of the first metal 60 and the second metal 64 . The metallic bond between the first metal 60 and the second metal 64 lowers the electrical resistance between the first metal 60 and the second metal 64, ensuring good conduction.

The first metal 60 includes a recess 62 whose interior is wider than the opening 62A. The second metal 64 enters a portion 62B of the recess 62 of the first metal 60, which is wider inside than the opening 62A. Furthermore, the second metal 64 is metal-bonded to the inner surface of the recess 62 of the first metal 60. This ensures that the first metal 60 and the second metal 64 have sufficient mechanical fastening strength and electrical continuity with low electrical resistance required for battery terminals.

The recess 62 of the first metal 60 may have, for example, a shape in which the recess 62 of the first metal 60 gradually widens in the depth direction. The depth of the recess 62 of the first metal 60 is preferably 0.2 to 2.0 with respect to the diameter of the opening 62A. Further, the ratio D ₂ /D ₁ between the diameter D ₁ of the recess 62 of the first metal 60 and the diameter D ₂ of the opening 62A is preferably 0.95 or less, more preferably 0.9 or less. preferable. Further, D ₂ /D ₁ is preferably 0.4 or more, more preferably 0.5 or more. By setting D ₂ /D ₁ to such a value, a space into which the second metal 64 enters the widened portion 62B of the recess 62 of the first metal 60 is suitably formed, and the first metal 60 and the second metal 64 can be well bonded. Note that the diameter of the recess 62 refers to the diameter of the widest portion of the cross section taken along the same depth from the opening 62A.

FIG. 7 is a cross-sectional view schematically showing a terminal component 54 according to another embodiment.
In the form shown in FIG. 7, a recess 62D is further formed at the bottom of the recess 62. The recess 62D is further provided with a portion 62B whose interior becomes wider in the depth direction from the opening of the recess 62D. The recess 62D has a shape in which a side circumferential surface 62C3 protrudes toward the inner diameter side with respect to the bottom portion 62C1. On the other hand, a portion 64A of the second metal 64 that has entered the recess 62 of the first metal 60 has also entered a recess 62D formed at the bottom of the recess 62. Furthermore, the first metal 60 and the second metal 64 are metal-bonded at the bottom of the recess 62D.

According to this embodiment, the portion 64A of the second metal 64 that has entered the recess 62 of the first metal 60 is the side circumference 62C2 of the recess 62 of the first metal 60 and the side periphery of the recess 62D formed at the bottom. It engages with both surface 62C3. Therefore, the first metal 60 and the second metal 64 are mechanically connected more strongly, and the electrical continuity required by a battery terminal with low electrical resistance is ensured.

In addition, in the form shown in FIG. 7, the recess 62D formed at the bottom has a substantially truncated conical space. The recess 62D may be anything that strengthens the mechanical bond between the first metal 60 and the second metal 64 that has entered the recess 62 of the first metal 60. From this point of view, the recess 62D formed at the bottom of the recess 62 of the first metal 60 is not limited to the shape shown in FIG. 7. For example, a plurality of recesses may be formed at the bottom of the recess 62. Furthermore, the recesses 62D formed in the bottom portion may be partial or may be formed intermittently in the circumferential direction.

In the form disclosed here, the first metal 60 of the terminal component 54 constituting the negative external terminal is made of copper, and the second metal 64 is made of aluminum. The first metal 60 of the terminal component 54 is joined to the copper negative current collector terminal 52 inside the battery case 30 . The second metal 64 of the terminal component 54 is joined to the aluminum bus bar 14 outside the battery case 30. By using such a terminal component 54 for the negative external terminal 54, good electrical conduction and bonding can be achieved with the copper negative current collector terminal 52 inside the battery case 30. Further, outside the battery case 30, the battery case 30 is well electrically connected and bonded to the aluminum bus bar 14. Further, the first metal 60 and the second metal 64 of the terminal component 54 have the required mechanical fastening strength, and furthermore, the electrical continuity required by the battery terminal with low electrical resistance is ensured. . Therefore, although the negative electrode external terminal 54 constituted by such a terminal component 54 is made of dissimilar metals such as copper and aluminum joined together, conduction failure is unlikely to occur even if external force such as vibration is applied from the bus bar 14.

By applying the terminal component disclosed herein to a secondary battery, it is possible to match the metal types of the portions of the positive and negative external terminals of the secondary battery that are connected to the bus bar. Therefore, adjacent cells in the assembled battery can be well connected.

A method of manufacturing the above-mentioned terminal component 54 will be explained. 8 and 9 are cross-sectional views illustrating a method of manufacturing the terminal component 54. The method for manufacturing the terminal component 54 includes a step of preparing a first metal 60, a step of preparing a second metal 64, and a step of metal-bonding the first metal 60 and the second metal 64.

In the step of preparing the first metal, a first metal having a recess 62 whose inside is wider than the opening 62A is prepared. In this embodiment, first metal 60 is comprised of copper. Since the shape of the first metal 60 is the same as that of the embodiment described above, detailed explanation will be omitted.
The first metal 60 is manufactured by, for example, forming a recess 62 in the first metal 60 by performing known metal processing such as forging or cutting on the metal that is the material of the first metal 60. be able to.

The recess 62 of the first metal 60 is designed to have dimensions such that the first metal 60 and the second metal 64 are mechanically joined with sufficient strength by inserting the second metal 64 in a later step. Good. In this embodiment, the recess 62 of the first metal 60 has a circular cross section. As shown in FIG. 8, the area of the bottom 62C1 of the recess 62 of the first metal 60 is larger than the area of the opening 62A, and the inner diameter becomes smaller from the bottom 62C1 toward the opening 62A.

In the step of preparing the second metal 64, a second metal having lower rigidity than the first metal is prepared. In this embodiment, the second metal 64 is a plate-shaped member made of aluminum. The shape and dimensions of the second metal 64 are appropriately set depending on the type of the second metal 64, the shape of the recess 62 in the first metal 60, and the like. The shape and dimensions of the second metal 64 are such that it can be inserted into the part 62B of the recess 62 of the first metal 60, which is wider inside than the opening, in a later process, and has enough strength that it will not be penetrated by pressing, which will be described later. There is no particular restriction as long as it has a thickness.

In the step of metal-bonding the first metal 60 and the second metal 62, the second metal 64 is overlapped on the portion of the first metal 60 where the recess 62 is formed. Then, the second metal 64 is partially pressurized in accordance with the position corresponding to the recess 62 of the first metal 60, thereby forming a recess 64C in the second metal 64, and opening 62A of the recess 62 of the first metal 60. A part of the second metal 64 is also inserted into the wide internal portion 62B. Further, a part of the second metal 64 that has entered the recess 62 of the first metal 60 and the first metal 60 are metallurgically bonded.

The metal bonding between the first metal 60 and the second metal 64 is performed, for example, by ultrasonic pressure welding. For example, as shown in FIG. 8, a first metal 60 is placed on an anvil 70. Next, a second metal 64 is placed on the surface of the first metal 60 having the recess 62 . Next, the horn 72 is pressed against the second metal 64. As a result, the first metal 60 and the second metal 64 are sandwiched between the anvil 70 and the horn 72. Here, the position where the horn 72 is pressed is the position corresponding to the recess 62 of the first metal 60 among the parts where the second metal 64 is overlapped with the first metal 60, that is, the position corresponding to the opening 62A of the recess 62. It's the location. The area where the horn 72 is pressed against the second metal 64 is set inside the opening 62A of the recess 62. The horn 72 used has a smaller area than the opening 62A.

Horn 72 is attached to a press (not shown) equipped with a vibration generator. As shown in FIG. 9, the horn 72 is pressed against the second metal 64 while being subjected to vibrations required for ultrasonic pressure welding. As a result, the second metal 64 is pushed into the recess 62 of the first metal 60. When the second metal 64 is pushed into the first metal 60, the second metal 64 is plastically deformed and deeply enters the recess 62 of the first metal 60, and a recess 64C is formed on the surface against which the horn 72 is pressed. Ru. Further, a portion of the second metal 64 that has entered the recess 62 of the first metal 60 and the first metal 60 are metal-bonded. The second metal 64 is pushed into the opening 62A of the first metal 60 to the extent that a recess 64C is formed in the surface against which the horn 72 is pressed. For this reason, a part of the second metal 64 can be inserted into the portion 62B of the recess 62 of the first metal 60, which is wider inside than the opening 62A. As a result, the side peripheral surface 62C2 of the recess 62 of the first metal 60 and the second metal 64 that has entered the recess 62 engage with each other. Therefore, the first metal 60 and the second metal 64 are mechanically firmly connected, and the first metal 60 and the second metal 64 are electrically connected with a low resistance required for a battery terminal. Ru. In this way, according to the method proposed here, the mechanical coupling and metal bonding between the first metal 60 and the second metal 64 are performed simultaneously. Therefore, the terminal component 54 can be manufactured with a small number of steps.

Here, the pressure applied from the horn 72 to the second metal 64 by the press machine is appropriately set according to the metal types and dimensions of the first metal 60 and the second metal 64, the shape of the horn 72, and the like. Although not limited thereto, the press pressure may be set to, for example, about 50 to 1600N.
The ultrasonic vibration applied via the horn 72 is appropriately set depending on the metal types and dimensions of the first metal 60 and the second metal 64, the shape of the horn 72, and the like. Although not limited thereto, for example, the amplitude can be set to about 20 to 80 μm, the frequency can be set to about 15 to 150 kHz, and the amount of energy given to the first metal 60 and the second metal 64 can be set to about 100 to 500 J.

In the embodiment described above, the first metal 60 and the second metal 64 are joined by applying pressure to a part of the second metal 64 while applying vibration to the horn 72. However, the present invention is limited to this embodiment. I can't do it. For example, first, the second metal 64 is pressurized, the second metal 64 is inserted into the recess 62 of the first metal 60, the second metal 64 and the bottom 62C1 of the recess 62 of the first metal 60 are brought into contact, and then the horn 72 is inserted. Metallic bonding may be performed by applying vibration. Further, in the embodiment described above, the first metal 60 and the second metal 64 are metal-bonded by ultrasonic pressure welding, but the present invention is not limited to this embodiment. The metal joining of the first metal 60 and the second metal 64 can be performed by a known method, for example, by friction welding, resistance welding, or the like.

As described above, when the second metal 64 is joined to the first metal 60 while forming the recess 64C, the bottom 64D of the recess 64C in the second metal is subjected to vibration while pressurizing the horn 72. Roughness and deformation can be seen due to the application. For example, when metal joining is performed by ultrasonic pressure welding, residues of the second metal 64 due to processing may remain on the bottom portion 64D. When metal joining is performed by friction welding, friction marks may remain on the bottom portion 64D due to pressure welding while rotating. When metal bonding is performed by resistance pressure welding, discoloration may be observed on the bottom portion 64D due to oxidation of the surface.

In the manufacturing method described above, simultaneously with pressurization, the bottom portion 62C1 of the recess 62 of the first metal 60 and the portion of the second metal that has entered the recess of the first metal are metal-bonded. In this way, by simultaneously performing mechanical bonding by pressurization and metal bonding, the terminal component 54 can be manufactured with a reduced number of steps. Further, since the second metal 64 is roughened and deformed on the bottom portion 64D due to metal bonding, it is possible to suppress roughness and deformation of the surface of the terminal component 54 that is connected to the bus bar or the like.

In the embodiments described above, the second metal 64 is less rigid than the first metal 60. This allows the second metal 64 to be plastically deformed with low pressure. As a result, the terminal component 54 can be manufactured with less roughness and deformation.

The dimensions of the recess 62 of the first metal 60 prepared in the step of preparing the first metal 60 are _not particularly limited, but for example, the ratio D ₂ /D 1 of the diameter D ₁ of the recess 62 and the diameter D ₂ of the opening 62A. is preferably 0.95 or less, more preferably 0.9 or less. Further, D ₂ /D ₁ is preferably 0.4 or more, more preferably 0.5 or more. By setting D ₂ /D ₁ to such a value, a space into which the second metal 64 enters the widened portion 62B of the recess 62 of the first metal 60 can be suitably formed.
When D ₂ /D ₁ is large, that is, close to 1, a part of the second metal 64 enters the part 62B that is wider inside than the opening of the recess 62 of the first metal 60. is not formed, making it difficult to maintain a bonded state. Furthermore, if D ₂ /D ₁ is small, a large gap may be formed between the recess of the first metal 60 and the second metal 64. In this case, when a large gap is formed, the second metal 64 is not in close contact with the inside of the recess 62 of the first metal 60, and the second metal 64 is not tightly attached to the first metal 60 when an external impact such as vibration is applied. There is a possibility that the bonded state of the second metal 64 cannot be maintained.

In the step of preparing the first metal 60, as shown in FIG. 7, a recess 62D may be further formed at the bottom of the recess 62 of the first metal 60. It is preferable that the recess 62D is provided with a portion that becomes wider in the depth direction from the opening. Such a recess 62D can be formed by performing metal processing on the first metal 60 using a known method.
By such a manufacturing method, the close contact state between the first metal 60 and the second metal 64 is suitably maintained, and the terminal component 54 is manufactured in which the first metal 60 and the second metal 64 are mechanically connected more strongly. can do.

Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The invention disclosed herein includes various modifications and changes to the above-described specific examples.

10 Assembled battery 11 Spacer 12 Secondary battery (single cell)
14 Bus bar 17 End plate 18 Tightening beam material 19 Screw 20 Electrode body 21 Positive electrode sheet 22 Negative electrode sheets 23, 24 Separator 30 Battery case 32 Battery case body 34 Lid 36 Gasket 38 Insulator 40 Positive terminal 42 Positive current collector terminal 44 Positive electrode external Terminal 50 Negative terminal 52 Negative current collector terminal 54 Terminal parts (negative external terminal)
54A Surface 60 First metal 60A Shaft 60B Upper end 60C Caulked portion 62 Recess 62A of first metal Opening 62B Part wider inside than opening 62C1 Bottom 62C2, 62C3 Side peripheral surface 62D Recess 64 Second metal 64A First Part of the metal that has entered the dent (intrusion part)
64B Part where the inside of the recess of the first metal is widened (inset part)
64C Recess 64D Bottom 66 Joint 70 Anvil 72 Horn

Claims (13)

a first metal;
a second metal overlaid on the first metal,
The first metal is
The part where the second metal is overlapped has a recess that is wider inside than the opening,
The second metal is
A portion has entered the recess of the first metal,
a portion of the recess of the first metal that has entered a portion that is wider inside than the opening;
a recess formed on a surface opposite to a portion of the first metal that has entered the recess;
A joint is formed in which at least a part of the second metal that has entered the recess of the first metal is joined to the inner surface of the recess of the first metal by ultrasonic pressure welding, friction welding, or resistance pressure welding. terminal parts. The terminal component according to claim 1, wherein the first metal has higher rigidity than the second metal. The opening and the cross section of the recess of the first metal along a cross section that traverses the same depth from the opening are each circular,
A diameter D ₁ of the widest cross section of the recess of the first metal along a cross section crossing the same depth from the opening and a diameter D ₂ of the opening are 0.4≦D ₂ /D ₁ ≦. The terminal component according to claim 1 or 2, which satisfies the relationship of 0.95. Claim 1: A recess is further formed at the bottom of the recess of the first metal, and the recess formed at the bottom is provided with a portion whose interior becomes wider in the depth direction from the opening. - Terminal parts listed in any one of 3. 5. The first metal is made of copper or a copper-based alloy, and the second metal is aluminum or an aluminum-based alloy. terminal parts. an electrode body including a positive electrode and a negative electrode;
a battery case housing the electrode body therein;
A secondary battery comprising a positive terminal and a negative terminal electrically connected to the positive electrode and the negative electrode, respectively, in the electrode body,
A secondary battery, wherein at least one of the positive electrode terminal and the negative electrode terminal includes the terminal component according to any one of claims 1 to 5. An assembled battery in which a plurality of single cells are electrically connected to each other and arranged,
An assembled battery in which the secondary battery according to claim 6 is used as the plurality of single cells. The plurality of unit cells have a positive terminal of one unit cell and a negative terminal of another unit electrically connected to each other by a bus bar,
The assembled battery according to claim 7, wherein the bus bar is made of the same metal as the second metal. preparing a first metal having a recess that is wider inside than the opening;
a step of preparing a second metal;
a step of metallurgically bonding the first metal and the second metal,
The metal joining step includes:
overlaying the second metal on the portion of the first metal where the recess is formed;
Partially pressurizing the second metal at a position corresponding to the recess in the first metal, forming a recess in the second metal, and forming a part wider inside than the opening of the recess in the first metal. Inserting a portion of the second metal,
A method for manufacturing a terminal component, comprising metal-bonding a portion of the second metal that has entered a recess in the first metal and the first metal by ultrasonic pressure welding, friction welding, or resistance pressure welding. 10. The method for manufacturing a terminal component according to claim 9, wherein in the step of preparing the second metal, a second metal having lower rigidity than the first metal is prepared. In the step of preparing the first metal ,
The opening and the cross section of the recess of the first metal along a cross section that traverses the same depth from the opening are each circular,
A diameter D 1 of the widest cross section of the recess of the first metal along a cross section crossing the same depth from the opening _and a diameter D ₂ of the opening are 0.4≦D ₂ /D ₁ The method for manufacturing a terminal component according to claim 9 or 10, wherein the first metal satisfying the relationship of ≦0.95 is prepared. In the step of preparing the first metal, a recess is further formed at the bottom of the recess, and the recess formed at the bottom is provided with a portion whose interior becomes wider in the depth direction from the opening. The method for manufacturing a terminal component according to any one of claims 9 to 11, wherein the first metal is prepared. In the step of preparing the first metal, a first metal made of copper or a copper-based alloy is prepared, and in the step of preparing the second metal, the first metal is made of aluminum or an aluminum-based alloy. The method for manufacturing a terminal component according to any one of claims 9 to 12, wherein the second metal is prepared.

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